Complete Precision Selections Using Channels

Another useful technique that helps you make precise selections involves using channels to seek higher contrast edges at the boundaries of your sought after selection. If you know upfront that you need an intricate selection boundary, you can start out on the Red channel to make the whole selection process easier and faster.

1 Choose WindowoChannels.

Doing so activates the Channels palette.

2 In the Channels palette, click on the Red channel.

The Red channel image appears on-screen.

The idea here is that, by activating the Red channel, I can use the relatively high contrast between sky and clouds to give me a precise edge to finish this selection process.

3 Continue your selection using the Magic Wand tool.

You may want to use a Tolerance setting around 10 to complete a selection like this.

4 Back in the Channels palette, select RGB to return to the composite image so that you can review the selection.

Other selection tools — such as the Color Range tool (choose SelectOColor Range) — use similar, Tolerance-like techniques to adjust pixel range. The Color Range's similar adjustment is called Fuzziness.

Photoshop Confidential

High-Quality Selection Secrets

One secret to creating high-quality selections in Photoshop is making the edges of your selections gradual or gradational, not abrupt. Abrupt edges are very obvious and scream, "Here is an edit!" Making sure that the pixels along the edges of your selections are semitransparent creates gradual or gradational edges. The semitransparent nature of a selection allows that edited selection to blend in with the surrounding areas of the image that have not been edited.

You can create semitransparent edges in numerous ways, including these: 1) creating an anti-aliased edge, 2) feathering an edge, and 3) blurring the edge of a mask of the selection. The method you use depends upon the image, the selection area, and what you intend to do with the selection. Being familiar with several methods for controlling the width and transparency of your selections grants you greater control over your image. In my experience, when you want to exert the greatest control over your selections, you will convert your selections to masks (either as a QuickMask or as a saved alpha channel mask) and then adjust those masks using blurring — blurring offers 0.1 pixel adjustments, compared with feathering, which works in full pixel increments — or by editing the masks with a soft edge of one of the painting brushes.

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